• Document: MICROALGAE FOR AQUACULTURE: CONVERTING ART INTO TECHNOLOGY. William van der Riet CEO Tomalgae, Belgium
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MICROALGAE FOR AQUACULTURE: CONVERTING ART INTO TECHNOLOGY William van der Riet CEO Tomalgae, Belgium TOMALGAE PRODUCES MICROALGAE (FOR LARVAL AQUACULTURE) MICROALGAE IN AQUACULTURE “Algae are at the base of the entire aquatic food chain,… Therefore, it is not surprising that the microalgae which compose the phytoplankton play a vital role in the rearing of aquatic animals like molluscs, shrimp, and fish, and have a strategic interest for aquaculture.” (Arnaud Muller-Feuga 2000) MICROALGAE IN AQUACULTURE “Since artificial substitutes are inferior to live microalgae as feed for the critical stages in the life cycles of several aqua-cultural species, a growing demand for microalgae will go hand in hand with the expected growth of aquaculture throughout the world.” (Amos Richmond 2007) MICROALGAE IN AQUACULTURE • “Presently, most aquaculture enterprises produce their own supply of microalgae.” (A. Richmond 2007) • “Mass production of micro-algae has been recognized as a major bottle-neck to many forms of marine hatchery and nursery production… The problem of high costs of individual hatcheries producing their own algae is compounded by the need of scarce expertise, without which crashes of algae at critical periods occur quite commonly.” (Heasman et al. 2001) • “This has prompted a search for alternatives to on-site production” • The most obvious alternative: centralized microalgae facilities that produce, concentrate and preserve the algae. MICROALGAE FARMING Production on an industrial scale Open ponds Closed Photobioreactors (PBRs) A pair of 200-foot algae open ponds at Sapphire Energy's Las Flat-plate “Acrylic” Photobioreactors. Photo by AzCATI: Cruces, New Mexico R&D Facility.Photo courtesy Sapphire Energy. http://asulightworks.com/blog/azcati-update-plastic-film-vs- acrylic-photobioreactors 6 MICROALGAE IN AQUACULTURE Principal applications: Aquaculture hatcheries (direct or indirect feed source, ‘green water’ technology) Ingredients for aquatic animal feeds- very limited, expensive (e.g. Spirulina) Microalgae ‘forms’ used: —Diatoms (Bacillariophyceae): Chaetoceros, Thalassiosira, Cyclotella, Skeletonema, Phaeodactylum —Green algae (Chlorophyta): Chlorella, Tetraselmis, Haematococcus, Dunaliella —Haptophyta: Isochrysis, Pavlova —Cryptophyta: Rhodonomas —Eustigmatophyceae: Nannochloropsis —Cyanophyta: Spirulina GENERALIZED ANALYSIS OF SELECTED MICROALGAE USED IN AQUACULTURE Criteria (characteristics) of cultures and their concentrates —Small cell size —Fast rate of growth —Nutritional value —Digestibility —Buoyancy —‘Resistance’ to grazing —Concentrate & Drying —Rehydration and (or) resuspension MICROALGAE IN (FOR) AQUACULTURE Haptophyta: Isochrysis • Small cell size • Fast rate of growth • Acceptable biochemical quality • Digestibility • Buoyancy • ‘Resistance’ to grazing • Concentrate and drying • Rehydration and or resuspension 9 MICROALGAE IN (FOR) AQUACULTURE Eustigmatophyceae: Nannochloropsis • Too small cell size • Fast rate of growth • Acceptable biochemical quality • Digestibility • Buoyancy • ‘Resistance’ to grazing • Concentrate and drying • Rehydration and or resuspension 1 MICROALGAE IN (FOR) AQUACULTURE Cryptophyta: Rhodonomas • Small cell size • Fast rate of growth • Acceptable biochemical quality • Digestibility • Buoyancy • Resistance’ to grazing • Concentrate and drying • Rehydration and or resuspension MICROALGAE IN (FOR) AQUACULTURE Spirulina, Chlorella and Tetraselmis are very poor in PUFAs contents in addition, very low digestibility for Tetraselmis Nanochloropsis Chlorella. Nannochloropsis contains EPA but Artemia exhibits very low digestibility of Nannochloropsis Chlorella Spirulina MICROALGAE IN (FOR) AQUACULTURE BACILLARIOPHYTA (DIATOMS): THALASSIOSIROID ‘CULTIVAR’ OF TOMALGAE —Small cell size (specific control) —Fast rate of growth (specific control) —Nutritional value (specific control) —Digestibility —Buoyancy —‘Resistance’ to grazing (rigorous control) —Concentrate (specific) & Drying (specific) —Rehydration and (or) resuspension (specific) OVERALL BIOCHEMICAL COMPOSITION Brown et all 1997. LONG-CHAIN PUFA’S CONTENT OF MICRO-ALGAE PRESERVED ALGAE

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